what are the requirements for mesh transformation using armatures
Requirements for a pose mode transformation of a bone to affect a mesh object:


Mesh must have an Armature Modifier with the armature set.
Mesh must have a weight group with the same name as the bone.


Since we usually also want the object to move, if we move the armature object as a whole, it is advisable to parent the mesh object to the armature object.

It is possible to setup a bone, which doesn't deform the mesh regardless of weight groups. This is done with the Deform option. It is enabled by default, you must have disabled it by accident.